Some types of nickel metal catalyst systems are available in the art. For example, nickel-phosphorus ligand catalyst systems have been used for hydrocyanation of butadiene to form pentenenitrile (PN) and for hydrocyanation of pentenenitrile to form adiponitrile (ADN). Examples of catalyst compositions and processes for the hydrocyanation of monoethylenically unsaturated compounds using zero-valent nickel and bidentate phosphite ligands in the presence of Lewis acid promoters include those described, for example in U.S. Pat. Nos. 5,512,696; 5,723,641; and 6,171,996.
Some nickel preparations and/or nickel complexes are also described, for example, in GB14607A, GB255884A, GB703826A, EP101733106A, EP0114704, EP0985448A1 and in U.S. Pat. Nos. 4,416,825 3,903,120; 3,496,217; 3,631,191; 3,816,098; 3,846,461; 3,847,959; 3,903,120; 4,118,342; 6,171,996; and 6,494,931.
Formation of hydrocyanation catalysts can involve formation of complexes between nickel atoms and phosphorus-containing ligands. However, commercially available sources of nickel often do not efficiently form these complexes. Moreover, different batches and lots of nickel from the same supplier often have different compositions and exhibit unpredictable activity for forming nickel-ligand complexes. For example, as illustrated herein, nickel starting materials from different batches and diverse commercial sources can exhibit up to 200% variability in their ability to form complexes with phosphorus-containing ligands. Different types of phosphorus-containing ligands also vary in their ability to form catalytic complexes with nickel. Such variability in complex formation by currently available nickel sources and ligands leads to low efficiency catalysts and manufacturing processes, as well as significant waste.
To solve the problems of inefficient nickel-ligand complex formation, manufacturers have previously employed activators such as phosphorus trichloride (PCl3) to promote the formation of catalytically active nickel complexes with monodentate phosphorus-containing ligands. See, e.g., U.S. Pat. No. 5,688,986 to Tam, Kreutzer & McKinney. However, such activators can react with some phosphorus-containing ligands and inactivate the ligands. Thus, the useful lifetime of catalysts can be shortened by use of activators. Therefore, improved nickel metal preparations and methods of making catalytically active nickel-ligand complexes are needed.